It seems that being climate conscious is now “in.” With several
documentaries airing this year on climate change, including Al Gore’s
An Inconvenient Truth, and politicians
and celebrities like Laurie and Larry David and Leonardo
DiCaprio taking up the topic as their cause célèbre,
the issues surrounding climate change seem to be more high-profile than
ever.

Along with these events has been an increase in public concern over the issue: In March, a poll by Time, ABC News and Stanford University indicated that 85 percent of Americans think that global temperatures are rising. And 80 percent think it’s at least in part due to human activities. Still, according to the poll, 64 percent of Americans perceive a lot of scientific disagreement about global warming.

Public awareness about climate change is not new, but it has certainly increased in the past year or two, says Nathan Hultman, a climate and policy professor at Georgetown University. Although some of that increase is probably due to celebrity exposure, he says, world factors, such as high gasoline prices and strong storms, have likely all conspired to bring climate change to the forefront of the public’s mind.

Still, celebrities are “coming together in this very chaotic mix that influences public opinion and policy,” Hultman says. Although it is unclear why celebrities are focusing on climate change and where they are getting their information, he says, their presence encourages higher visibility of the topic and thus more vigorous public debate.

Hultman points to Princeton University climatologist Michael Oppenheimer’s appearance on Oprah in October 2005 to talk about climate change. Invited on the show with Leonardo DiCaprio, Oppenheimer would have never had a chance to get on the show by himself, Hultman says, but with DiCaprio’s help, Oppenheimer was able to reach a new audience. “And that’s not necessarily a bad thing,” Hultman says.

The primary concern about celebrities getting involved, Hultman says, is that misinformation about climate change could permeate the public consciousness. Take, for example, An Inconvenient Truth: Much of the science was well-researched, Hultman says. “And I don’t think Gore ever outright made any outrageous assertions, but there were a couple of times when he put in a couple of questionable juxtapositions,” such as narration describing the hydrologic changes expected with warming while showing pictures of Hurricane Katrina. Such juxtapositions could lead viewers to the conclusion that Katrina could have been caused by global warming — but “we don’t have a clear scientific consensus yet on the links between warmer temperatures and individual storms,” so that is a premature conclusion and a “disservice to science,” he says.

Still, Hultman says, overall the movie “contributes greatly to the climate debate” in the United States. Furthermore, like DiCaprio and other celebrities, Gore is “getting out there and telling not only what the science is, but also why this is an important topic.”

The one thing Gore and other celebrities are missing, however, is offering
big-picture solutions, says Roger Pielke Jr., a
political scientist at the Center for Science and Technology Policy Research
in Colorado. “It doesn’t do a whole lot to just promote awareness,
if no solutions are offered,” Pielke says, or if the solutions are
“change your lightbulb, plant a tree or something equally”
insignificant in the grand scheme.

Some events this year tried “carbon neutrality” solutions to offset the carbon dioxide emissions they generated, such as the Super Bowl in Detroit, for which the National Football League planted 2,400 trees, and the FIFA World Cup of soccer, which invested about $1.5 million in alternative energy projects. But while such efforts are a small step forward, Pielke says, they are largely symbolic only. And he worries that large, yet insignificant, actions such as these will cause people to think they are done and move on.

Scientists especially need to be careful to offer options, rather than
to advocate one particular solution, Pielke says, as that’s where
they can lose credibility with the public. For example, despite offering
good science from renowned climatologists, all of this year’s TV
documentaries on climate change — such as HBO’s Too
Hot Not to Handle by Laurie David, and the Discovery Channel’s
Global Warming: What You Need to Know with
Tom Brokaw — are advocacy pieces, Pielke says. “They’re
political documentaries with science in them,” he says.

Although such programs do add to the public consciousness, the problem
still remains that they may be sending the wrong message. “In the
end, we experts need to be very upfront,” he says, about the long-term
nature of the problem.

Even though 2006 brought a quiet Atlantic hurricane season, with only nine named storms through mid-November, the debate over whether or not global warming is causing more intense hurricane seasons seemed to grow louder.

Several papers were published on the topic this year, with some saying that it is too early to tell whether warming has or will affect hurricanes, and others saying that warming has already worsened storm intensity and that the trend will continue. An ancillary question — whether human activities or natural cycles are the primary drivers of warming sea-surface temperatures — also received attention.

In general, these questions have not been resolved with any certainty, says Tom Karl, director of the National Oceanic and Atmospheric Administration’s National Climatic Data Center. And these issues will be an important part of a new U.S. Climate Change Science Program report on extreme weather and climate change, which is expected to be published in 2008, he says. Karl notes, however, that recent research findings have brought more information to light, and it has now become “clear that for the first time, there is credible scientific evidence to support the notion that humans are having an impact on the intensity of tropical storms.”

Several factors affect a hurricane’s formation and strength, including sea-surface temperatures, atmospheric stability, and wind and circulation changes in the atmosphere, wrote Patrick Michaels, a climatologist at the University of Virginia and the Cato Institute, and colleagues in the May 10 Geophysical Research Letters (see Geotimes, July 2006). His and others’ research this year tried to discern exactly which factors were affecting hurricanes the most. Michaels’ team found that sea-surface temperatures play a relatively smaller role in the strength of storms than other issues not related to climate change, such as stability in the atmosphere.

Other such studies showed the opposite, however, including a paper by Carlos Hoyos of Georgia Tech and colleagues in the April 7 Science, which linked the trend of increasing sea-surface temperatures in Atlantic hurricane-formation zones to the number of Category-4 and -5 hurricanes, a number that increased from 1970 to 2004. That observation matches what most models predict, Karl says: that hurricanes increase their windspeeds and produce heavier precipitation as they move over warm waters. So, all other things being equal, warmer temperatures mean more intense storms, he says.

The question of whether sea-surface temperatures are the primary factor in increasing hurricane intensity “is where honest people can disagree, simply because of the perspective from which they’re looking at the question,” Karl says. But even though a better understanding of all the factors that could intensify storms is needed, he says that the debate over whether hurricanes will strengthen if global sea-surface temperatures continue to warm should be put to rest.

“Models show more intense storms with heavier precipitation,” Karl says. And to date, “no one has shown in any model results that you can actually get less intense storms with rising sea-surface temperatures.” The issue of whether sea-surface temperatures are rising faster due to human activities should also be put to rest, he says. Several lines of research have shown that increasing levels of greenhouse gases in the atmosphere are causing increasing sea-surface temperatures.

In the Sept. 19 Proceedings of the National Academy of Sciences, Benjamin Santer of Lawrence Livermore National Laboratory, Tom Wigley of the National Center for Atmospheric Research and colleagues wrote that human activity is to blame for increased sea-surface temperatures. Santer’s team ran 80 simulations with 22 different climate models to separate the human impact from the natural impact. In some of the models, the team fixed atmospheric levels of greenhouse gases at pre-Industrial levels. The team then ran models with the greenhouse gas levels from the past couple of centuries.

A comparison of the models indicated that natural climate variability could not alone explain the observed increases in sea-surface temperatures. “Human-caused increases in greenhouse gases were by far the largest single contribution to the overall warming of sea-surface temperatures” in the Atlantic and Pacific hurricane-formation regions, Santer and Wigley wrote in a Sept. 11 press release.

In all of these studies, understanding the veracity of past records of hurricane intensity, and how well those records can help deduce present and future changes, is important — and that issue has also been heavily debated this year, Karl says. It will be interesting to watch the scientific research results that come out over the next few years, he adds.

In the meantime, Karl says, people need to remember to think long term — and that may entail putting less infrastructure and fewer people in the paths of hurricanes.

The hydrologic cycle is inexorably linked to global climate, so any climate change can alter how the planet stores and recycles water. With some prognoses suggesting that the increasing temperatures will cause the global water cycle to intensify — leading to more droughts, floods and fires — researchers are keeping a careful eye on how warming is affecting one of Earth’s largest and most important freshwater storage systems: the glaciers and snowpack resting atop the world’s highest mountain ranges.

Although data are limited at high altitudes, evidence indicates that glacier retreat is under way in all Andean countries, including Chile, Columbia and Venezuela, where mountain communities rely on the glaciers for their drinking water. According to Raymond Bradley and colleagues in the June 23 Science, while such a retreat initially spikes runoff, it can cause trouble over the long term, by removing a “glacial buffer” during the dry season.

Last summer in Wyoming, researchers at the National Center for Atmospheric Research launched this driftsonde — a balloon outfitted with weather instruments. Such instruments can help observe important details about atmospheric conditions during hurricane formation. Photograph is by Joseph VanAndel; copyright of UCAR.

Not only the High Andes are at risk, however. Higher latitude glaciers, such as those in the European Alps, could be gone by 2100, if average summer air temperatures increase by 5 degrees Celsius, according to a model by Michael Zemp and colleagues in the July 15 Geophysical Research Letters. Melts this severe could affect hydrological cycles, water management practices, tourism and the occurrence of natural hazards in high-mountain areas.

Like glaciers, snowpacks provide a consistent supply of freshwater to people around the world during dry seasons, according to a study by Tim Barnett of the Scripps Institution of Oceanography, and colleagues (see Geotimes, March 2006). Even a small change in temperature can cause precipitation to fall as rain, which washes quickly out to sea, rather than snow, Philip Mote, the state climatologist of Washington, told Geotimes in March. The loss of snowpack, as well as glaciers, could cause significant shortages of freshwater in regions from the western United States to the Himalaya and the South American Andes, according to the study. So far, the largest declines in snowpack have occurred in mountainous regions with milder climates, but colder regions are also at risk, Barnett’s team reported.

Other scientists are continuing to monitor how climate changes have already affected water distribution around the world. Maarten de Wit and Jacek Stankiewicz reported in the March 31 Science that nearly one-fourth of Africa could face serious water shortages by 2100 from severe drought. And in July, Brazil’s Environment Minister, Marine da Silva, suggested that an ongoing severe drought in the country — which began in 2005 and lasted through September — was brought on by warmer temperatures in the North Atlantic and the Gulf of Mexico creating warmer air currents that blocked rain clouds from forming.

Meanwhile, other parts of the world have been wetter: A study by Kerstin Treydte of the Swiss Federal Research Institute WSL and colleagues found that tree-ring analyses suggest that the mountains in northern Pakistan have seen more precipitation over the past century than over the past millennium (see Geotimes online, Web Extra, April 28, 2006). The researchers suggest the increases may be greater than natural variability. They also found that the increases are coincident with increases in atmospheric carbon dioxide.

Finally, combining climate models with a global vegetation model, earth system modeler Marko Scholze of the University of Bristol reported predictions of more regional drought, floods and fires for the next 200 years in the Aug. 21 Proceedings of the National Academy of Sciences. In his study, Scholze suggested that an average global temperature increase of 2 degrees Celsius is inevitable, even if greenhouse gas emissions cease immediately.

That change would increase the probability of drought, and the world would lose much of its forests, Scholze wrote. If temperatures increase by an average of 3 degrees Celsius worldwide due to continuing greenhouse gas emissions, he said, the models foretell a more dangerous scenario, with more forests lost, flooding in some regions and drought and less freshwater in other parts of the world.

This year, methane’s effects on climate have been in the spotlight. Several studies examined how the natural gas contributes to understanding past climate change, as well as how the gas should factor into models that predict future global change.

Hinrich Schaefer and colleagues collect ice samples from Greenland to measure past levels of methane in the atmosphere. Photograph is by Joe Melton.

Two lines of research, one by Todd Sowers of Pennsylvania State University and another by Hinrich Schaefer of Oregon State University and colleagues, used new dates from bubbles in Greenland ice to show that during the last three abrupt warming periods — at 38,000, 14,500 and 11,500 years ago — methane spikes simultaneously occurred with or even slightly after the warming began (see Geotimes, April 2006). Their isotopic results also pointed to a terrestrial source of the methane, effectively ruling out that the methane spikes were the result of massive releases of the gas from the seafloor, as previously hypothesized.

“I think these results are pretty conclusive,” Ed Brook, a paleoclimatologist at Oregon State University and a co-author on the Schaefer et al. paper in the Aug. 25 Science, told Geotimes in April. It would be difficult to reconcile the seafloor methane hypothesis with these results, he said.

The question of what else could cause the methane spikes at these time periods remains up for debate, however. One paper, published by Glen MacDonald and colleagues in the Oct. 13 Science, indicated that methane released by peat bogs in the northernmost one-third of the planet probably helped fuel a major period of warming approximately 11,000 to 12,000 years ago that drew Earth out of the last ice age.

Perhaps one of the most surprising methane findings this year, however, was a study by Frank Keppler and colleagues that posited that plants produce large amounts of methane (see Geotimes online, Web Extra, Jan. 13, 2006). The researchers say that all the plants on Earth today could account for at least 10 to 30 percent of the total amount of methane in the atmosphere.

The finding could lead scientists to reevaluate ecosystem models, as previous research had indicated that methane generation was primarily a microbial and anoxic process. And it could change climate models: methane contributions from plants have not been included in models that predict future greenhouse gas emissions or warming from methane.

Kate Moran and Jan Backman led a decade-long crusade to drill in the
Arctic, finally accomplishing their goals in 2004. In 2006, the science
began to come to light in various publications. Here is a snapshot
of the important findings, according to Moran (see Geotimes,
August 2006).

Sedimentation
occurs in the Arctic at nearly the same rate as other ocean basins
 previously, scientists had bantered about the idea that the
basin was starved of sediment.

During the Paleocene-Eocene
Thermal Maximum (PETM), "the Arctic was warm, very warm,"
Moran says. Temperatures in the Arctic Ocean may have reached 24
degrees Celsius during the PETM, and 18 degrees Celsius before and
after it. Not only are those numbers drastically higher than climate
models have predicted, but they also indicate that there was not
much of a gradient between temperatures at the equator and at the
pole during this climate event. Today, such a finding might imply
that as Earth warms, the Arctic could warm at an increased rate,
she says. Much controversy still surrounds this interpretation of
the core, however.

 Not long after
that, the Arctic might have been a huge freshwater lake, as evinced
by massive freshwater ferns called azola. The finding has significant
implications for the Arctic's hydrologic cycle, as the Arctic is
often considered a cold desert.

 Ice-rafted debris
began to show up around 45 million years ago, 30 million years earlier
than scientists thought ice had existed in the Arctic, and close
to the same time that Antarctica iced over. This find could overturn
previous thinking that the planet cooled first in Antarctica and
cooled much later in the Northern Hemisphere as ocean circulation
changed and tectonic passageways opened and closed, Moran says.
This find suggests that both places cooled simultaneously, which
implicates greenhouse gases as the cause of the cooling, as opposed
to tectonic plate movement.

 The team thinks
that they can discern sea ice from icebergs in the record, which
would enable the researchers to figure out when the Arctic iced
over, Moran says (see main story).

The team plans to present their research at the annual fall meeting
of the American Geophysical Union in San Francisco this month, and
to publish a special issue of Paleooceanography, as well
as other suites of papers with further results of their research.

MS

In 2004, Kate Moran broke the ice — literally — on past Arctic
climate change, becoming part of the first team to drill the Lomonosov
Ridge in the central Arctic Ocean. It was a project Moran and others had
dreamt about and planned for since 1991. This year, the first scientific
studies were published from the Arctic drilling expedition, with surprising
results for Arctic climate change, Moran says.

Moran,
a professor at the University of Rhode Island, calls herself an oceanographer,
but comes from a background in civil and marine engineering. That background
allows her to “take a step back and examine better the big science
issues — ask the big science questions,” she says.

Oceanographer Kate Moran (left) examines the core pulled up from the Arctic Ocean — the first of its kind. Photograph is by Jan Backman.

When Moran went on her first Ocean Drilling Program expedition across
the Arctic Ocean in 1991, she says that she found it “stunning how
much we didn’t know about the Arctic.” Even the maps they
had were off by half a kilometer or more, Moran says. On that trip, they
crossed the Lomonosov Ridge. “It was very clear to us that we had
to go back there and drill that ridge because it represented a climate
record that we needed,” Moran says.

For the next 10 years, she worked to drum up support for their risky endeavor
to drill the Arctic — risky because no one had done it before, and
it was unknown whether icebreaker ships could both penetrate the thick
sea ice and remain stable enough to drill deep below the ice to bring
up a core. Over that long period, “Moran was extremely good at shaping
the plan and keeping everyone’s interest up,” says Jan Backman,
a friend and colleague at Stolkholm University, who worked with Moran
on the drilling project. “I don’t know that anyone else could
have accomplished this.”

By 2003, Moran and her colleagues finally convinced their sponsors, including
the governments involved in the Ocean Drilling Program, that they had
the technical capability to drill in the Arctic. In late summer 2004,
they traveled to the Arctic. The team was excited and nervous, Backman
says, “as Kate and I had heard that if we didn’t succeed,
it would have closed the doors to drilling in the Arctic for another 30
years.”

But Moran never lost focus or optimism, Backman says, even when things
got dicey as drill bits broke and they encountered thicker ice cover than
they had imagined. Instead of despairing, Moran brought her exceptional
understanding of the technical processes and her wide net of contacts
to the table, and solved the problems, says Larry Mayer, an oceanographer
at the University of New Hampshire and long-time colleague of Moran.

Once in the Arctic, “it was all very exciting,” Moran says. The first thrill came when the icebreakers actually began drilling, and “we realized this was going to work,” she says. Then the science began, as the team pulled up the core, and found a layer of freshwater ferns and evidence of the global warming event known as the Paleocene-Eocene Thermal Maximum (PETM). They knew that they had recovered a temperature record of the Arctic going back at least 55 million years, and they were elated. Further research on the cores since returning home has revealed a record dating back to 80 million years ago, Moran says, and has uncovered much about the Arctic’s past climate, which is far different than scientists once imagined (see Geotimes, August 2006).

Like a parent asked to name their favorite child, Moran finds it difficult to choose just one find of the expedition as the most significant. But when pressed, she points to a yet-unpublished result: The team thinks that they can pick apart evidence of sea ice from evidence of icebergs in the core, which would enable the researchers to figure out when the Arctic iced over, Moran says.

Sea ice is a moderator of climate, she says. Its reflectivity may decrease temperatures and thus increase the snow cover, possibly sending the world into an ice age. If the researchers can see just how rapidly the sea ice formed, they can “look at it in relation to other major climate change periods and see if we can better understand how Earth moves into that major climate change,” she says.

The researchers hope to learn much more as they continue to study the core, Moran says. The work is causing them to think about climate change a little bit differently — “about greenhouse gas forcing, how ice can change the planet, and so on, and those are pretty significant things,” she says.

There are big science questions remaining in the Arctic, and Moran hopes to be a part of answering those questions. She and colleagues currently have a proposal before the Integrated Ocean Drilling Program to go back to the Arctic. And this time, it shouldn’t take them a decade to get there.